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Thread parameter in ANSI C makes a segmentation fault

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# 1  
Old 05-05-2011
Thread parameter in ANSI C makes a segmentation fault
The creation of thread.
Code:
void Client_Constructor ( const char* IPAddr ) {
    pthread_t tid; 
    pthread_attr_t rx;  

    /* Create separate memory for client argument */
    struct ThreadArgs *threadArgs;
    if ( ( threadArgs = ( struct ThreadArgs* ) malloc( sizeof( struct ThreadArgs ) ) ) == NULL )
        exit( -1 );
    threadArgs->pos = 111;

    pthread_rwlock_wrlock( &rwlock );
    node = ....;
    if ( node->state == DISCONNECTED ) {  <-node requires a r/w lock.
        pthread_attr_init( &rx );
        pthread_attr_setdetachstate( &rx, PTHREAD_CREATE_DETACHED );
        pthread_create( &tid, &rx, THREAD_BODY, ( void* )threadArgs );
    }
    pthread_rwlock_unlock( &rwlock );
}

Thread body
Code:
static void* THREAD_BODY ( void* v ) {
    int sockfd;
    char IPStr[ 16 ];
    int index = ( ( struct ThreadArgs* ) v )->pos; free( v ); <-segmentation fault here
.....
}

These code is so strange, when I run the program more than few hours, then a segmentation fault comes. I also dump the log and use gdb to analyze it, the information is shown below
Code:
Program terminated with signal 6, Aborted.
#0  0xb7de1a16 in ?? () from /lib/libc.so.6
(gdb) where
#0  0xb7de1a16 in ?? () from /lib/libc.so.6
#1  0xb7de3318 in ?? () from /lib/libc.so.6
#2  0xb7e1cfdd in fputws () from /lib/libc.so.6
#3  0xb7e1d114 in ?? () from /lib/libc.so.6
#4  0xb7e287ba in realloc () from /lib/libc.so.6
#5  0xb7e28040 in ?? () from /lib/libc.so.6
#6  0xb7e28339 in ?? () from /lib/libc.so.6
#7  0xb7e2476b in ?? () from /lib/libc.so.6
#8  0x0805e945 in THREAD_BODY (v=0x1838b9b0) at Client.c:167
#9  0xb7efffc0 in pthread_create@@GLIBC_2.1 () from /lib/libpthread.so.0
#10 0xb7e8497e in ?? () from /lib/libc.so.6

It anyone give me some suggestions? Is it related to pthread_rwlock?
# 2  
Old 05-05-2011
Are you working on Linux? If so, can you run your program under valgrind supervision?
This User Gave Thanks to Loic Domaigne For This Post:
sehang
# 3  
Old 05-05-2011
Quote:
Originally Posted by Loic Domaigne
Are you working on Linux? If so, can you run your program under valgrind supervision?
Thanks. I try it now. However, I can run the program under the text mode only since our system doesn't have a GUI. Is valgrind able to work in text mode?
# 4  
Old 05-05-2011
Try fprintf(stderr, "%p\n", v); to see if the pointer value has become corrupted somehow.

If all you're passing is one integer, why allocate memory at all?

void *value=(void *)42;
int ivalue=(int)(value);

If that's not all you're doing, post a more complete portion of your code so we can see what's actually going on.
This User Gave Thanks to Corona688 For This Post:
sehang
# 5  
Old 05-05-2011
Quote:
Originally Posted by Corona688
Try fprintf(stderr, "%p\n", v); to see if the pointer value has become corrupted somehow.

If all you're passing is one integer, why allocate memory at all?

void *value=(void *)42;
int ivalue=(int)(value);

If that's not all you're doing, post a more complete portion of your code so we can see what's actually going on.
Thanks, I will use fprintf to catch the pointer value.

Before I post the problem on the forum, I tried to use
Code:
 void *value=(void *)42;
  int ivalue=(int)(value);

But the problem still happened. At that time, I wrote these codes in another way; it is the reason why I use struct to pass parameters.

I have another idea, is it the problem cause by different compile options?
Code:
 gcc -O3 *.c

Code:
  gcc *.c

However, I have 10-20 source files in the project, it is difficult to put all codes in this forum.

Besides, I used outl(...), iopl(...) to control SPI. Are they also affect this threading?
# 6  
Old 05-05-2011
Quote:
Originally Posted by sehang
Thanks, I will use fprintf to catch the pointer value.

Before I post the problem on the forum, I tried to use
Code:
 void *value=(void *)42;
  int ivalue=(int)(value);

But the problem still happened.
Then the problem has nothing to do with that line.
Quote:
I have another idea, is it the problem cause by different compile options?
Code:
 gcc -O3 *.c

Code:
  gcc *.c

-O3 by itself doesn't cause it to crash. However it can expose latent bugs in your program.
Quote:
Besides, I used outl(...), iopl(...) to control SPI. Are they also affect this threading?
This is an extremely poor design and I can't guarantee anything about it. Given the way modern systems work I can't even guarantee you're actually talking to I/O ports. Is it possible to use an actual device driver instead?
# 7  
Old 05-05-2011
Quote:
Originally Posted by Corona688
Then the problem has nothing to do with that line. -O3 by itself doesn't cause it to crash. However it can expose latent bugs in your program. This is an extremely poor design and I can't guarantee anything about it. Given the way modern systems work I can't even guarantee you're actually talking to I/O ports. Is it possible to use an actual device driver instead?
So that means using -O3 in multi-threading is a bad idea?
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